1. Field of the Invention
This invention relates to masking machines.
More particularly, the invention relates to apparatus of the type especially adapted for dispensing sheet material and tape for use in masking surfaces.
In a further and more specific aspect, the present invention concerns improvements for enhancing the utility of conventional masking machines
2. The Prior Art
The prior art is replete with various devices, generally referred to as masking machines, which are especially useful during preparation for finishing procedures such as painting and trimming. Commonly, the devices dispense sheet material and tape for application to a surface for protection from a finish or treatment applied to an adjacent surface. Familiar exemplary uses are observed in building decoration and in automotive body finishing.
Having achieved substantial success, masking machines are commercially available in a variety of sizes and configurations to accommodate various specific uses Noted, for example is the relatively large, bulky apparatus known as an apron machine. Being stationarily mounted, this machine dispenses an apron of taped sheet for application to a remote surface. Equally notable is the relatively lightweight, compact hand held masking machine which is moved over a surface as sheet material and tape are concurrently dispensed and applied.
Commonly, masking machines include a frame having a holder for carrying a roll of coiled sheet material and another holder for supporting a roll of coiled, pressure sensitive tape. The holders, which are rotatably mounted upon spindles and have parallel axis of rotation, are oriented such that the tape is applied along and overlapping an edge of the sheet material during dispensing. An elongate cutting edge, also carried by the frame and extending parallel to the axis of the holder, serves to sever the tape and sheet material. The hand held units further include a handle.
Masking machines were originally devised for use in combination with sheet material and tape having widths within defined finite limits. Sheet material for hand held machines, for example, usually had a width in the range of four inches to eighteen inches. The larger apron machines could accommodate sheet material as wide as forty-eight inches. Tape having a width of one-half or three-fourths inch was usable with both.
Conventionally, masking sheet material has been in the form of a relatively heavyweight paper which has been treated to be substantially liquid impervious. A desired length of the paper sheet, having been trimmed to a selected width, is coiled about a paper core.
Coiled from flat stock, the finished roll has a width which is synonymous with the width of the paper sheet. The size of a roll, width and length of the coiled sheet material, which is usable in combination with a hand held machine is confined within practical limits of bulk and weight. While weight is generally not a consideration in connection with apron machines, the spacing between frame members imposes a limitation upon the maximum width of roll.
Recently, considerable attention has been directed to increasing the versatility of masking machines through the use of extended width sheet material. To this end, the art has advanced the use of plastic material, such as polyethylene, which can be folded and refolded prior to being coiled. Accordingly, sheet material having a width several times the previous standard has become possible.
The use of plastic sheet material, however, has revealed certain previously unrecognized limitations of prior art masking machines. In contrast to the firm, unyielding, edge of a roll of conventional paper sheet, a roll of folded plastic sheet presents a soft, flexible edge as a result of the peculiarities of folding. Accordingly, mutual deflection occurs between the tape and the tape receiving edge of the sheet material. The phenomenon is enhanced by the smooth, slick surface of the plastic.
Experimentation has also detected another factor which inhibits satisfactory adherence of the tape to the edge of the sheet material. Tape being drawn from a roll has an inherent tendency to track laterally. The lateral displacement, which is directly proportional to the cohesiveness and to the width of the tape, negates the desired overlapping alignment between the tape and the edge of the coiled sheet material. Although particularly pronounced in combination with the soft edge of a roll of folded plastic sheet, the problem exists independent of the composition or configuration of the sheet material.
Further identified is another area of interest and concern. Users of masking machines frequently carry an auxiliary roll of tape particularly for the purpose of taping along the free edge of an applied sheet. For convenience, the prior art has provided means for supporting an independently usable roll of tape upon the frame of the masking machine.
In accordance with the prior art, the device is installed upon the frame by permanent means, such as a screw. Therefore, the device, an auxiliary tape dispensing unit, is limited to use in combination with the masking machine.
Accordingly, it is an object of the present invention to provide improvements for masking machines.
Another object of the invention is the provision of means whereby a masking machine is readily usable with alternate coiled sheet material, such as folded plastics.
And another object of the invention is to provide means which accommodate the use of exceedingly wide tape.
Still another object of the instant invention is the provision of improvements for guiding and tacking tape from the roll thereof to the roll of sheet material.
Yet another object of the invention is to provide improved means for aligning and applying tape upon the edge of a roll of sheet material.
Yet still another object of this invention is the provision of improved means for mounting an auxiliary roll of tape upon a masking machine.
And a further object of the invention is to provide means whereby an auxiliary tape dispenser is quickly and conveniently attachable to or removable from a masking machine.
Yet a further object of the immediate invention is the provision of improvements which can be readily practiced in connection with prior art masking machines.
Still a further object of the invention is to provide improvements which will materially enhance the utility of the masking machine without introducing encumbrances.
And yet a further object of the invention is the provision of improvements, according to the above, which can be simply and economically practiced with conventional skills and procedures.